The invention relates to a boom lift product and, more particularly, to supporting structure for a boom lift product that is expandable and retractable between a stowed/transport position and a working position.
It is desirable with a boom lift product to provide a stable and secure base when a platform supported at an end of an extendible boom is used in a raised position. Stability can be achieved through the use of outriggers, counterweights and the like. A wider wheel base also provides added stability, but a wider wheel base has limitations for transport since a width of the more stable wheel base typically exceeds maximum limitations for transport or on-road travel.
It would be desirable for supporting structure for a boom lift product to include an adjustable wheel base that is wider in a working position and narrower for transport.
Existing machines of this type use a single axle extend cylinder for each axle pair connected between the two associated axles. One deficiency it has is the extension cylinder is relatively low to the ground and relatively unprotected from impact damage such as might be seen when driving into a low object like a fire hydrant or the like. The existing designs may include a slide bar to protect the rod itself but the cylinder as a whole is unprotected from structural deflection or damage. This is of particular concern for a system such as this for if or when the cylinder is impacted, the force of contact may allow the angle of the axle to change as the cylinder deforms (if the cylinder is no longer straight, the distance between the connections to the axles and or frame would be shorter). This would result in the axles retracting to some extent unintentionally and would risk the machine stability due to a shifting of the tip line of the machine.